The present invention relates to a multilayer body, a piezoelectric element, and a liquid ejecting device. More specifically, the invention relates to a multilayer body having a substrate and a low-resistance metal layer, a piezoelectric element in which such a multilayer is used, and a liquid ejecting device which includes such a piezoelectric element.
Piezoelectric elements having a piezoelectric film endowed with piezoelectric properties that expands and contracts with the rise and fall in the intensity of an applied electric field and electrodes that apply an electric field to the piezoelectric film are used in, for example, the actuators built into ink-jet recording heads. Ink-jet recording heads have a construction that includes a pressure chamber which communicates with an ink feed chamber, and ink ejection ports which communicate with the pressure chamber. A vibration plate having a piezoelectric element bonded thereto is provided in the pressure chamber. In such a construction, by applying a specific voltage to the piezoelectric element and causing it to expand or contract, flexural oscillations are generated, which oscillations in turn compress the ink within the pressure chamber, causing droplets of ink to be ejected from the ink ejection ports.
The piezoelectric element used in such an ink-jet recording head is generally composed of a piezoelectric layer and two electrode layers—an upper electrode layer and a lower electrode layer—on either side of the piezoelectric layer. Of these, it is desired that the lower electrode layer have a low electrical resistance and good thermal resistance. For example, in the piezoelectric vibratory element described in JP 2003-158309 A, the material making up this lower electrode layer is composed primarily of one of the following: platinum, gold, silver, rhodium, rhenium, osmium or iridium. In the thin-film piezoelectric element described in JP 2002-164586 A, the lower electrode layer contains at least one of the following: platinum, iridium, palladium, rhodium or gold. Of these materials, a gold layer—i.e., a layer containing gold as a constituent material—is disclosed on account of the excellent thermal resistance and other properties of such a layer.